Destratification system and air diffuser unit for user therein

ABSTRACT

The system employs a plurality of submerged diffuser units spaced along a supply air feed line and an air-water discharge valve device disposed at the downstream end of the feed line to permit expulsion of substantially all water present in the feed line at the commencement of an operating period. The diffuser units are in the form of air jet reaction propellers, which effect vertical circulation by both mechanical and diffused air pumping.

United States Patent [1 1 Hunt Jan. 1, 1974 [54] DESTRATIFICATION SYSTEMAND AIR 1,579,355 4/1926 Granwalt 261/93 DIFFUSER UNIT FOR USER THEREIN3,626,500 12/1971 Dummann 261/122 X 3,677,936 7/1972 Bastiaanse 261/124X [76] Inventor: Harold G. Hunt, 389 Fillmore Ave.,

East Aurora, NY. 14052 [22] Filed: Apr. 3, 1972 [21] Appl. No.1 240,689

[52] US. Cl 261/65, 210/220, 261/87, 261/121 R [51] Int. Cl BOlf 3/04[58] Field of Search 210/123, 127, 219, 210/220; 261/65, 87,93,121R,l22,124

[56] References Cited UNITED STATES PATENTS 3,242,072 3/1966 Walker261/124 X 2,597,931 5/1952 Hano 261/124 X Primary ExaminerSamih N.Zaharna Assistant ExaminerRobert H. Spitzer Att0rneyJohn B. Bean et a1.

[57] ABSTRACT The system employs a plurality of submerged diffuser unitsspaced along a supply air feed line and an airwater discharge valvedevice disposed at the downstream end of the feed line to permitexpulsion of substantially all water present in the feed line at thecommencement of an operating period. The diffuser units are in the formof air jet reaction propellers, which effect vertical circulation byboth mechanical and diffused air pumping.

10 Claims, 8 Drawing Figures see sum 20; 2

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DESTRATIFICATION SYSTEM AND AIR DIFFUSER UNIT FOR USER THEREINBACKGROUND OF THE INVENTION Thermal stratification occurs in manyreservoirs, because of the detention time required for water to flowthrough the impoundment and the rate of heat exchange between thereservoir surface and the atmosphere. The water adjacent the surface ofthe reservoir constantly undergoes changes in temperature because ofenvironmental conditions and such changes in temperature are accompaniedby corresponding changes in water density. Thus, in the winter months,the colder, denser surface water settles and forces the bottom water tomove upward. This vertical circulation and resultant aeration of thedeep bottom water tends to produce a uniform quality of water in areservoir. However, during the late spring and-summer months, thewarmer, less dense surface water restricts circulation and aeration ofthe bottom waters, resulting in the classical three layer thermo-pattemincluding the epilimnion, thermocline and hypolimnion.

The epilimnion, or upper layer, is generally of a good quality(containing 6 ppm. to ppm. dissolved oxygen) and may be from between to30 feet deep according to the depth of the reservoir. The thermocline,or intermediate layer of water, is characterized as having rapidlydecreasing temperature changes and a marginal quality (2 ppm. to 6 ppm.dissolved oxygen). Usually, dissolved oxygen concentrations decreaserapidly with depth in the thermocline. The hypolimnion, or

A lower layer, is cold and has little or no dissolved oxygen.

Since withdrawals of water from the epilimnion, or upper layer only, isimpracticable and not consistent with the economical use of availablewater, present large reservoirs often discharge oxygen poor water fromthe lower water levels during the late summer and early fall months.Studies have indicated that such oxygen poor water has an adverse effecton the quality of the water for biological, domestic, and industrialuses downstream.

To date, numerous methods for improving the water quality of reservoirimpoundment have been considered. Present systems feature theintroduction of oxygen into the water in the hypolimnion layer in orderto change its density sufficiently to cause vertical circulation andmixing of all strata in the reservoir. Oxygen introduction has beenvariously achieved, such as for instance by supplying pressurized air toa perforated pipe.

Various problems with all systems are to be expected on the basis ofeffectiveness vs. cost considerations. In present systems not employingcomplex backflow preventing valving arrangements difficulties will beencountered during system start up after a shut down with regard to theremoval of water, which tends to completely fill the system duringperiods of non-use.

SUMMARY OF THE INVENTION The present invention is directed towards asystem and an improved air diffuser unit for use in effectingdestratifaction and the introduction of oxygen into bodies of water.

More specifically, the system of the present invention features anarrangement wherein a plurality of submerged diffuser units are spacedalong a supply air feed line and an air-water discharge valve device isdisposed at the downstream end of the feed line for the purpose ofpermitting expulsion of substantially all water present in the feed lineat the commencement of an operating period.

The diffuser units forming a part of the present invention are air jetreaction propellers, which serve to effect vertical circulation of waterby both mechanical and diffused-air pumping techniques. Further, thepresent diffuser units incorporate a simple low cost construction,wherein the pressure of the supply air is employed to counter-balancegravity and circulation induced forces acting on the units duringoperation.

DRAWINGS The nature and mode of the present invention will now be morefully described in the following detailed description taken with theaccompanying drawings wherein:

FIG. 1 is a diagrammatic, elevational view illustrating thedestratification system of the present invention installed in areservoir or the like;

FIG. 2 is an enlarged view taken generally along the line 22 in FIG. 1;

FIG. 3 is a sectional view taken generally along line 3-3 in FIG. 2;

FIG. 4 is a sectional view taken generally along line 4-4 in FIG. 3;

FIG. 5 is an enlarged view taken generally along line 5-5 in FIG. 1;

FIG. 6 is a side elevational view of the diffuser unit illustrated inFIG. 5;

FIG. 7 is a partial sectional view taken generally along the line 7-7 inFIG. 5; and

FIG. 8 is a sectional view taken generally along line 8-8 in FIG. 5.

DETAILED DESCRIPTION Reference is now made particularly to FIG. 1,wherein the system of the present invention is generally designated as10 and shown as being arranged within a lower level of a body of water12 subject to a thermal stratification condition. The body of water maybe an artificial impoundment, such as is created by a dam, or a naturalimpoundment, such as a lake.

More specifically, system 10 includes in its simplest form a supply airfeed line or conduit 14; a plurality of branch ducts l6 spaced apartalong an elongated, essentially horizontally disposed section of conduit14; a plurality of air diffuser units 18, which are rotatably supportedon branch ducts 16 in flow communication with feed line 14; and anair-water discharge valve device 20, which is disposed adjacent thedownstream end of feed line 14. It will be understood that line 14 issuitably anchored by means, not shown, in order to position diffuserunits 18 and valve device 20 in a spaced relationship above the floor ofthe reservoir or lake.

When system 10 is in use, air or other suitable oxygen containing fluidunder pressure is introduced into line 14 from a suitable above groundsource, such as compressor 22, for subsequent discharge by diffuserunits 18 upwardly into body of water 12. As will be apparent, thepressure and flow rate at which air is supplied to the feed line willdepend on various system parameters, including for instance the numberand discharge flow rates of diffuser units 18. Also, it will be apparentthat the number of diffuser units per feed line, and the length,diameter, number and orientation of the feed lines employed will dependupon the size and depth of the body of water to be treated. Further, itwill be understood that the flow cross-sectioned area of the feed lineand/or its branch ducts may be varied to insure uniform pressure airsupply to its associated diffuser units.

Now referring particularly to FIGS. 5-8, it will be understood that eachof diffuser units 18 is in the form of a jet reaction propellerconsisting essentially of a contoured upper piece 24 and a flat bottomplate 26, which may be formed of any suitable corrosive resistantmaterial. Upper piece 24 and plate 26 cooperate to define a centrallydisposed hub portion forming a plenum chamber 28, which is arranged inflow communication with an associated branch duct 16, and a plurality ofhollow wedge-shaped blades 30, which are arranged to extend radially ofand in flow communication with chamber 28. The hollow interior of eachof blades 30 is in turn placed in flow communicaion with the body ofwater in which the diffuser unit is immersed by means of orifices 32,which are formed in the base or rear wall 34 of blades 30, which isdefined by upper piece 24.

As best shown in FIG. 7, bottom plate 26 is formed with an aperturedimensioned to freely receive an associated feed line branch duct 16,and is retained for rotation thereon by branch duct mounted, upper andlower bearing collars 38 and 40, respectively, which are suitably fixedto the branch duct by set screws or other suitable fasteners 42.

As by way of example, diffuser unit 18 may be mounted on its associatedbranch duct 16 by the successive operations of fixing lower bearingcollar 40 to the branch duct; sliding bottom plate 26 downwardly overthe branch duct into supporting engagement with lower bearing collar 40;fixing upper bearing collar 38 to the branch duct such as to free thebottom plate for limited vertical movement between the bearing collars;and finally joining upper piece 24 to the bottom plate. In a preferredconstruction illustrated in the drawings, upper piece 24 and plate 26are joined together to complete the diffuser unit by means of generallyU-shaped metal clips or clamps 44. However, other suitable means, suchas adhesive or threaded fasteners, not shown, may be employed tocomplete assembly of the diffuser unit.

As will be apparent, when air under pressure is admitted to plenumchamber 28, such air is permitted to escape through orifices 32 as finejets, which tend to create thousands of minute bubbles from which oxygenis absorbed by the water. This serves to decrease the density of thewater and thereby promote a natural vertical circulation thereof.Moreover, the jets of escaping air produce a torque for effectingrotation of blades 30 in the direction indicated by arrow 45; the bladesthereby positively producing vertical circulation of the water to adegree depending upon their number, configuration and pitch. On thetheory that water absorbs oxygen proportionately to the area contacted,the orifices are preferably designed to produce small bubbles in orderto maximize the surface area forany given volume of air flow.

An ideal arrangement is achieved when the forces acting on the diffuserunit 18 are nearly balanced such that bottom plate 26 is disposedintermediate and in non-contacting relationship with upper and lowerbearing collars 38 and 40, and the annular space between the bottomplate and branch duct 16 is such as to permit air from plenum chamber 28to bleed downwardly and create an effective air bearing. Balancing ofthe diffuser unit is obtained when the downward thrust on the unitresulting from upward circulation of the water induced by rotation ofblades 30 is equal to the buoyancy of the plenum chamber and blades plusthe upward thrust of the supply air on the top wall 46 of the hubportion, which defines the upper boundary of the plenum chamber. Theoptimum area of the top wall and duct 16 outlet opening may becalculated for any given operating air pressure and blade design. Aswill be apparent, when the diffuser unit is balanced under operatingconditions, less friction and wear will occur at the bearing points andthere will be an overall increase in efficiency.

While blades 30 have been shown as being hollow and straight, and formedwith air jet defining discharge orifices 32, it is contemplated thatvarious other types and shapes of hollow blades may be employed to givemore effective hydraulic efficiency. Also, as by way of furtherillustration, the blades may be solid and employed to carry exteriorlymounted tubes, which are connected to the plenum chamber and definedischarge orifices adjacent their radially outer end.

When the system is not in use, such as during the winter and springmonths, the entire system may fill with water. In the usual dead endtype feed line or pipe, excessive pressures are required to clear waterfrom the feed line when it is desired to renew operation. Since ofttimesthe available pressure is insufiicient or the required pressure is inexcess of system design, water may not be completely removed fromadjacent the downstream end of the feed line with the result that one ormore of the diffuser units or other discharge devices will remainblocked with water and be rendered inoperative. To overcome thisproblem, the present system incorporates the above mentioned air-waterdischarge valve device 20.

Now referring particularly to FIGS. 2-4, it will be seen that valvedevice 20 includes a valve plate or flap cover 50, which is secured tofeed line 14 for free vertical pivotal movement between conduit endclosed and open positions by a hinge device 52; a latch bar 54, which issecured to feed line 14 for vertical pivotal movement by a hinge device56 and formed with an end cam lug 58 for retaining valve plate 50 inclosed position; and an air float device 60, which is interconnected tolatch bar 54 for conjunctive movement by a rod 62 freely extendingthrough vertically aligned feed line apertures 64. More specifically,float 60 is in the form of a downwardly open sheet metal or plasticshell, which is connected to rod 62 by a transversely extending bracingplate 66 and formed adjacent its upper surface with one or more airbleed orifices 68. When the system is not in operation, float 60 isfilled with water and supported in its phantom line position illustratedin FIG. 3 by a feed line mounted, support bracket 70.

When the system is in use, the elements of valve device 20 are disposedin their full line positions illustrated in FIG. 3; a sufficientquantity of the air escaping from the feed line through apertures 64being collected within float 60-inorder to'substantially entirelydisplace water therefrom. In this respect, it will be understood thatthe rate at which air escapes from bleed apertures 68 is substantiallyless than the rate at which air is supplied to the float from the feedline. If the rate at which air escapes through aperture 64 is notsufficient, the feed line may be provided with additional apertures 72and internally disposed air flow direction control baffles 74.

At the initiation of a period of non-use, air will gradually bleed fromfloat 60 through bleed apertures 68 such that the float will graduallyfill with water and sink to its phantom line position illustrated inFIG. 3. When this occurs, latch bar 54 moves into its unlatchedposition, wherein lug 58 is removed from latching engagement with valveplate 50. When feed line 14 has become filled with water enteringthrough the diffuser units, as well as through apertures 64 and 72, thewater pressure across valve plate 50 will be balanced, but the weight ofthe valve plate will continue to maintain same in closed position.

When the system is to be returned to use, pressure of the supplied airon the water within the feed line will force valve plate 50 to open inorder to permit flow of water outwardly through the downstream end ofthe feed line. The air pressure will be maintained until the feed lineis essentially free of water and float 60 has been raised to returnlatch bar 54 to its full line latched position shown in FIG. 3. At thispoint, the supply of air is momentarily interrupted in order to allowthe valve plate to drop under the influence of gravity and be locked inclosed position by lug 58; the lug being cammed downwardly 'by thevalveplate to permit closing thereof and immediately returned to lockedposition by the float. lmmediately thereafter the supply of air will bere-established to maintain air in the feed line under normal design oroperating pressure. It will be understood that the amount of airescaping from float 60 through bleed apertures 68 is insufficient topermit lowering of the float and latch bar 54 into unlatching positionduring the extremely short period of time that the air flow isinterrupted to permit the gravity lowering of valve plate 50. Thus,float 60 may be characterized as being responsive to the condition ofthe gas supply or source, that is, the float serves to place latch bar54 in its latching and unlatching positions when the gas supply isoperable and inoperable, respectively.

As will be apparent from the foregoing, l have devised an improvedsystem for effecting destratification and oxygenation of bodies ofwater. Moreover, it will be understood that while the disclosed diffuserunit and valve device constructions are preferably used in combination,they possess individual novelty and may therefore be separately employedin modification of existing systems.

I claim:

l. A system for effecting thermal destratification of a body of water bythe introduction of oxygen containing gas into a lower level thereof,which comprises in combination:

an oxygen containing gas supply conduit including an elongated sectionessentially horizontally disposed within said lower level;

gas supply means selectively operable for supplying gas under operatingpressure to one end of said conduit section;

a plurality of gas discharge means spaced apart lengthwise of saidconduit section for discharging gas therefrom into said lower level whensaid gas supply means is in operation, said discharge means permittingflow of water into said conduit section for collection therein when saidgas supply means is not in operation; and

a valve device arranged adjacent an other end of said conduit oppositeto said one end, said valve device including movable means, latch meansand means responsive to said gas supply means, said movable meanstending to move from an other end closed position into an other end openposition when said gas supply means is in operation and to move fromsaid other end open position into said other end closed position whensaid gas supply means is not in operation, said latch means beingmovable between unlatching and latching positions, said latch means whenin unlatching position permitting movement of said member between saidpositions thereof, said latch means when in latching position permittingmovement of said member from said other end open position into saidother end closed position while latching said memberfrom movement fromsaid other end closed position into said other end open position, andsaid responsive means placing said latch means in said unlatching andlatching positions when said gas supply means is not in operation and inoperation, respectively.

2. A system for effecting thermal destratification of a body of water bythe introduction of oxygen containing gas into a lower level thereof,which comprises in combination:

an oxygen containing gas supply conduit including an elongated sectionessentially horizontally disposed within said lower level;

gas supply means selectively operable for supplying gas under operatingpressure to one end of said conduit section;

a plurality of gas discharge means spaced apart lengthwise of saidconduit section for discharging gas therefrom into said lower level whensaid gas supply means is in operation, said discharge means permittingflow of water into said conduit section for collection therein when saidgas supply means is not in operation; and

a valve device arranged adjacent an other end of said conduit oppositeto said one end for normally closing said other end when said gas supplymeans is in operation, while permitting discharge through said other endof water collected in said conduit section when said gas supply means isreturned to operation, said valve device comprising a valve platehingedly mounted on said other end of said conduit section for verticalpivotal movement between other end open and closed positions; gassupportable float means, said float means having an aperture forbleeding gas therefrom at a given rate; a latch device for releasablylatching said valve plate in said closed position; connecting means forcoupling said float means and latch means for conjunctive movement; andfloat gas supply means for supplying gas to said float means from saidconduit section at a rate in excess of said given rate when said gassupply means is in operation whereby to expel water from said floatmeans and lift said float means into a first position, said aperturepermitting said float means to slowly fill with water and sink into asecond position when said float means is not supplied with gas by saidfloat gas supply means, said latch device being disposed in valve platelatched and unlatched positions when said float means is in said firstand second positions, respectively, said valve plate being adapted tomomentarily move said latch device from latched to unlatched positionduring movement of said valve plate from open to closed positionthereof, and said valve device being characterized in that upon returnof said gas supply means to operation after a period of non-operationduring which water collects in said conduit section and said float meansfills with water to move same into its second position said valve plateis initially forced into open position by collected water dischargedfrom said other end of said conduit section by gas within said conduitsection whereafter said float means is lifted into said first positionby gas supplied by said float gas supply means, that upon momentaryinterruption of operation of said gas supply means after said collectedwater is discharged and said float menas is lifted as aforesaid saidvalve plate is forced by gravity to move from said open into said closedposition and effect momentary movement of said latch device asaforesaid, and that upon immediate return of said gas supply means tooperation said float means is maintained in said first position thereofwhereby to maintain said latch means in said latched position to therebymaintain said valve plate in said closed position.

3. A system according to claim 2, wherein said latch device is supportedbeneath said other end of said conduit section for vertical pivotalmovement between latched and unlatched positions, said float means isdownwardly open and disposed above said other end of said conduitsection, said float gas supply means includes at least verticallyaligned openings formed adjacent said other end of said conduit sectionbelow said float means, said connecting means includes rod means freelyextending through said aligned openings and connected adjacent upper andlower ends thereof to said float means and said latch device.

4. A system according to claim 2, wherein said conduit section includesvertically upstanding branch ducts spaced apart lengthwise of saidconduit section; and each said discharge means comprises a gas jetreaction propeller supported for rotation on one of said branch ducts ingas flow communication with said conduit section, each said propellerincludes upper and lower parts and means for joining said parts, saidparts being configured to define a centrally disposed hub portionbounding a plenum chamber arranged inflow communication with anassociated branch duct and a plurality of blades for effecting upwardcirculation of water when said propeller is rotated, said bladesextending radially from said hub portion and having reaction gas jetdefining orifices arranged at least adjacent their radially outer endsfor effecting rotation of said propeller, said orifices being in flowcommunication with said chamber, and said lower part being journaled onsaid associated branch duct.

5. A system according to claim 4, wherein said blades are hollow forplacing said orifices in flow communication with said chamber asaforesaid.

6. A system according to claim 5, wherein said upper part is contoured,said lower part is a flat plate having an opening therethrough forfreely receiving said associated branch duct, and said associated branchduct carries vertically spaced collar bearings for retaining said lowerpart for limited vertical movement therebetween.

7. A system for effecting thermal destratification of a body of water bythe introduction of oxygen containing gas into a lower level thereof,which comprises in combination:

an oxygen containing gas supply condiut including an elongated sectionessentially horizontally disposed within said lower level, said conduitsection includes vertically upstanding branch ducts spaced apartlengthwise of said conduit section;

gas supply means selectively operable for supplying gas under operatingpressure to one end of said conduit section;

a plurality of gas discharge means spaced apart lengthwise of saidconduit section for discharging gas therefrom into said lower level whensaid gas supply means is in operation, said discharge means permittingflow of water into said conduit section for collection therein when saidgas supply means is not in operation, each said discharge meanscomprises a gas jet reaction propeller supported for rotation on one ofsaid branch ducts in gas flow communication with said conduit section,each said propeller includes a centrally disposed hub portion bounding aplenum chamber arranged in flow communication with an associated branchduct and a plurality of blades for effecting upward circulation of waterwhen said propeller is rotated, said blades extending radially from saidhub portion and having reaction gas jet defining orifices arranged atleast adjacent their radially outer ends for effecting rotation of saidpropeller, said orifices being in flow communication with said chamber,an upper end of said associated branch duct freely extends upwardlythrough an opening in a lower boundary wall of said chamber andcooperates with said opening to define an annular space through whichgas may pass from said chamber to provide a gas bearing between saidupper end and said lower boundary wall, said associated branch ductcarrying spaced upper and lower bearing means for retaining said lowerboundary wall for limited vertical movement therebetween, and saidchamber having an upper boundary wall whereby gas passing into saidchamber from said associated branch duct produces an upwardly directedforce on said propeller, said force cooperating with the bouyancy of thepropeller to essentially balance a downwardly directed reaction forceproduced on said propeller by upward circulation of said water uponrotation of said blades; and

a valve device arranged adjacent an other end of said conduit oppositeto said one end for normally closing said other end when said gas supplymeans is in operation, while permitting discharge through said other endof water collected in said conduit section when said gas supply means isreturned to operation.

8. In a system for promoting vertical circulation of a body of waterincluding source means for supplying an oxygen containing gas underpressure, conduit means arranged in flow communication with said sourceand submerged gas discharge means for discharging gas from the conduitmeans into the water, the improvement comprising:

said conduit means includes a vertically upstanding duct; and

said discharge means comprises a gas jet reaction propeller supportedfor rotation adjacent an upper end of said duct in gas flowcommunication with said conduit means, said propeller including acentrally disposed hub portion bounding a plenum chamber arranged inflow communication with said duct and a plurality of blades foreffecting upward circulation of water when said propeller is rotated,said blades extending radially from said hub portion and having reactiongas jet defining orifices for effecting rotation of said propeller, saidorifices being in flow communication with said chamber, an upper end ofsaid duct freely extending upwardly through an opening in a lowerboundary wall of said chamber and cooperating with said opening todefine an annular space through which gas may pass from said chamber toprovide a gas bearing between said upper end and said lower boundarywall, said duct carrying spaced upper and lower bearing means forretaining said lower boundary wall for limited vertical movementtherebetween, and said chamber having an upper boundary wall whereby gaspassing into said chamber from said duct produces an upwardly directedforce on said propeller, said force cooperating with the bouyancy of thepropeller to essentially balance a downwardly directed reaction forceproduced on said propeller by upward circulation of said water uponrotation of said blades.

9. In a system for promoting vertical circulation of a body of waterincluding source means for supplying an oxygen containing gas underpressure, conduit means arranged in flow communication with said sourceand submerged gas discharge means for discharging gas from the conduitmeans into the water, the improvement comprising: I

said conduit means includes a vertically upstanding duct; and

said discharge means comprises a gas jet reaction propeller supportedfor rotation adjacent an upper end of said duct in gas flowcommunication with said conduit means, said propeller including acentrally disposed hub portion bounding a plenum chamber arranged inflow communication with said duct and a plurality of blades foreffecting upward circulation of water when said propeller is rotated,said blades extending radially from said hub portion and having reactiongas jet defining orifices for effecting rotation of said propeller, saidorifices being in flow communication with said chamber,

said blades are hollow for placing said orifices inflow communicationwith said chamber as aforesaid, each said propeller includes upper andlower parts cooperating to define said hub portion and said blades andmeans for joining said parts, said upper part is contoured, said lowerpart is a flat plate having an opening therethrough for freely receivingan upper end of said duct whereby to journal said propeller on said ductand provide for gas flow communication between said chamber and saidduct, said flat plate opening and said duct cooperating to define anannular space through which gas may pass from said chamber to provide agas bearing between said flat plate and said duct, and said duct carriesvertically spaced collar bearings for retaining said lower part forlimited vertical movement therebetween.

10. A system for efiecting thermal destratification of a body of waterby the introduction of oxygen containing gas into a lower level thereof,which comprises in combination:

an oxygen containing gas supply conduit including an elongated sectionessentially horizontally disposed within said lower level;

gas supply means selectively operable for supplying gas under operatingpressure to one end of said conduit section;

a plurality of gas discharge means spaced apart lengthwise of saidconduit section for discharging gas therefrom into said lower level whensaid gas supply means is in operation, said discharge means permittingflow of water into said conduit section for collection therein when saidgas supply means is not in operation; and

a valve device arranged adjacent an other end of said conduit oppositeto said one end and being responsive to operation of said gas supplymeans for permitting discharge through said other end of water collectedin said conduit section when said gas supply means is returned tooperation, for closing said other end upon momentary interruption ofoperation of said gas supply means after said collected water isdischarged and for maintaining said other end closed during operation ofsaid gas supply means after said momentary interruption.

1. A system for effecting thermal destratification of a body of water bythe introduction of oxygen containing gas into a lower level thereof,which comprises in combination: an oxygen containing gas supply conduitincluding an elongated section essentially horizontally disposed withinsaid lower level; gas supply means selectively operable for supplyinggas under operating pressure to one end of said conduit section; aplurality of gas discharge means spaced apart lengthwise of said conduitsection for discharging gas therefrom into said lower level when saidgas supply means is in operation, said discharge means permitting flowof water into said conduit section for collection therein when said gassupply means is not in operation; and a valve device arranged adjacentan other end of said conduit opposite to said one end, said valve deviceincluding movable means, latch means and means responsive to said gassupply means, said movable means tending to move from an other endclosed position into an other end open position when said gas supplymeans is in operation and to move from said other end open position intosaid other end closed position when said gas supply means is not inoperation, said latch means being movable between unlatching andlatching positions, said latch means when in unlatching positionpermitting movement of said member between said positions thereof, saidlatch means when in latching position permitting movement of said memberfrom said other end open position into said other end closed positionwhile latching said member from movement from said other end closedposition into said other end open position, and said responsive meansplacing said latch means in said unlatching and latching positions whensaid gas supply means is not in operation and in operation,respectively.
 2. A system for effecting thermal destratification of abody of water by the introduction of oxygen containing gas into a lowerlevel thereof, which comprises in combination: an oxygen containing gassupply conduit including an elongated section essentially horizontallydisposed within said lower level; gas supply means selectively operablefor supplying gas under operating pressure to one end of said conduitsection; a plurality of gas discharge means spaced apart lengthwise ofsaid conduit section for discharging gas therefrom into said lower levelwhen said gas supply means is in operation, said discharge meanspermitting flow of water into said conduit section for collectiontherein when said gas supply means is not in operation; and a valvedevice arranged adjacent an other end of said conduit opposite to saidone end for normally closing said other end when said gas supply meansis in operation, while permitting discharge through said other end ofwater collected in said conduit section when said gas supply means isreturned to operation, said valve device comprising a valve plaTehingedly mounted on said other end of said conduit section for verticalpivotal movement between other end open and closed positions; gassupportable float means, said float means having an aperture forbleeding gas therefrom at a given rate; a latch device for releasablylatching said valve plate in said closed position; connecting means forcoupling said float means and latch means for conjunctive movement; andfloat gas supply means for supplying gas to said float means from saidconduit section at a rate in excess of said given rate when said gassupply means is in operation whereby to expel water from said floatmeans and lift said float means into a first position, said aperturepermitting said float means to slowly fill with water and sink into asecond position when said float means is not supplied with gas by saidfloat gas supply means, said latch device being disposed in valve platelatched and unlatched positions when said float means is in said firstand second positions, respectively, said valve plate being adapted tomomentarily move said latch device from latched to unlatched positionduring movement of said valve plate from open to closed positionthereof, and said valve device being characterized in that upon returnof said gas supply means to operation after a period of non-operationduring which water collects in said conduit section and said float meansfills with water to move same into its second position said valve plateis initially forced into open position by collected water dischargedfrom said other end of said conduit section by gas within said conduitsection whereafter said float means is lifted into said first positionby gas supplied by said float gas supply means, that upon momentaryinterruption of operation of said gas supply means after said collectedwater is discharged and said float means is lifted as aforesaid saidvalve plate is forced by gravity to move from said open into said closedposition and effect momentary movement of said latch device asaforesaid, and that upon immediate return of said gas supply means tooperation said float means is maintained in said first position thereofwhereby to maintain said latch means in said latched position to therebymaintain said valve plate in said closed position.
 3. A system accordingto claim 2, wherein said latch device is supported beneath said otherend of said conduit section for vertical pivotal movement betweenlatched and unlatched positions, said float means is downwardly open anddisposed above said other end of said conduit section, said float gassupply means includes at least vertically aligned openings formedadjacent said other end of said conduit section below said float means,said connecting means includes rod means freely extending through saidaligned openings and connected adjacent upper and lower ends thereof tosaid float means and said latch device.
 4. A system according to claim2, wherein said conduit section includes vertically upstanding branchducts spaced apart lengthwise of said conduit section; and each saiddischarge means comprises a gas jet reaction propeller supported forrotation on one of said branch ducts in gas flow communication with saidconduit section, each said propeller includes upper and lower parts andmeans for joining said parts, said parts being configured to define acentrally disposed hub portion bounding a plenum chamber arranged inflow communication with an associated branch duct and a plurality ofblades for effecting upward circulation of water when said propeller isrotated, said blades extending radially from said hub portion and havingreaction gas jet defining orifices arranged at least adjacent theirradially outer ends for effecting rotation of said propeller, saidorifices being in flow communication with said chamber, and said lowerpart being journaled on said associated branch duct.
 5. A systemaccording to claim 4, wherein said blades are hollow for placing saidorifices in flow communication with said chambEr as aforesaid.
 6. Asystem according to claim 5, wherein said upper part is contoured, saidlower part is a flat plate having an opening therethrough for freelyreceiving said associated branch duct, and said associated branch ductcarries vertically spaced collar bearings for retaining said lower partfor limited vertical movement therebetween.
 7. A system for effectingthermal destratification of a body of water by the introduction ofoxygen containing gas into a lower level thereof, which comprises incombination: an oxygen containing gas supply condiut including anelongated section essentially horizontally disposed within said lowerlevel, said conduit section includes vertically upstanding branch ductsspaced apart lengthwise of said conduit section; gas supply meansselectively operable for supplying gas under operating pressure to oneend of said conduit section; a plurality of gas discharge means spacedapart lengthwise of said conduit section for discharging gas therefrominto said lower level when said gas supply means is in operation, saiddischarge means permitting flow of water into said conduit section forcollection therein when said gas supply means is not in operation, eachsaid discharge means comprises a gas jet reaction propeller supportedfor rotation on one of said branch ducts in gas flow communication withsaid conduit section, each said propeller includes a centrally disposedhub portion bounding a plenum chamber arranged in flow communicationwith an associated branch duct and a plurality of blades for effectingupward circulation of water when said propeller is rotated, said bladesextending radially from said hub portion and having reaction gas jetdefining orifices arranged at least adjacent their radially outer endsfor effecting rotation of said propeller, said orifices being in flowcommunication with said chamber, an upper end of said associated branchduct freely extends upwardly through an opening in a lower boundary wallof said chamber and cooperates with said opening to define an annularspace through which gas may pass from said chamber to provide a gasbearing between said upper end and said lower boundary wall, saidassociated branch duct carrying spaced upper and lower bearing means forretaining said lower boundary wall for limited vertical movementtherebetween, and said chamber having an upper boundary wall whereby gaspassing into said chamber from said associated branch duct produces anupwardly directed force on said propeller, said force cooperating withthe bouyancy of the propeller to essentially balance a downwardlydirected reaction force produced on said propeller by upward circulationof said water upon rotation of said blades; and a valve device arrangedadjacent an other end of said conduit opposite to said one end fornormally closing said other end when said gas supply means is inoperation, while permitting discharge through said other end of watercollected in said conduit section when said gas supply means is returnedto operation.
 8. In a system for promoting vertical circulation of abody of water including source means for supplying an oxygen containinggas under pressure, conduit means arranged in flow communication withsaid source and submerged gas discharge means for discharging gas fromthe conduit means into the water, the improvement comprising: saidconduit means includes a vertically upstanding duct; and said dischargemeans comprises a gas jet reaction propeller supported for rotationadjacent an upper end of said duct in gas flow communication with saidconduit means, said propeller including a centrally disposed hub portionbounding a plenum chamber arranged in flow communication with said ductand a plurality of blades for effecting upward circulation of water whensaid propeller is rotated, said blades extending radially from said hubportion and having reaction gas jet defining orifices for effectingrotation of said propeller, said orifices being in flow communicationwith said chamber, an upper end of said duct freely extending upwardlythrough an opening in a lower boundary wall of said chamber andcooperating with said opening to define an annular space through whichgas may pass from said chamber to provide a gas bearing between saidupper end and said lower boundary wall, said duct carrying spaced upperand lower bearing means for retaining said lower boundary wall forlimited vertical movement therebetween, and said chamber having an upperboundary wall whereby gas passing into said chamber from said ductproduces an upwardly directed force on said propeller, said forcecooperating with the bouyancy of the propeller to essentially balance adownwardly directed reaction force produced on said propeller by upwardcirculation of said water upon rotation of said blades.
 9. In a systemfor promoting vertical circulation of a body of water including sourcemeans for supplying an oxygen containing gas under pressure, conduitmeans arranged in flow communication with said source and submerged gasdischarge means for discharging gas from the conduit means into thewater, the improvement comprising: said conduit means includes avertically upstanding duct; and said discharge means comprises a gas jetreaction propeller supported for rotation adjacent an upper end of saidduct in gas flow communication with said conduit means, said propellerincluding a centrally disposed hub portion bounding a plenum chamberarranged in flow communication with said duct and a plurality of bladesfor effecting upward circulation of water when said propeller isrotated, said blades extending radially from said hub portion and havingreaction gas jet defining orifices for effecting rotation of saidpropeller, said orifices being in flow communication with said chamber,said blades are hollow for placing said orifices in flow communicationwith said chamber as aforesaid, each said propeller includes upper andlower parts cooperating to define said hub portion and said blades andmeans for joining said parts, said upper part is contoured, said lowerpart is a flat plate having an opening therethrough for freely receivingan upper end of said duct whereby to journal said propeller on said ductand provide for gas flow communication between said chamber and saidduct, said flat plate opening and said duct cooperating to define anannular space through which gas may pass from said chamber to provide agas bearing between said flat plate and said duct, and said duct carriesvertically spaced collar bearings for retaining said lower part forlimited vertical movement therebetween.
 10. A system for effectingthermal destratification of a body of water by the introduction ofoxygen containing gas into a lower level thereof, which comprises incombination: an oxygen containing gas supply conduit including anelongated section essentially horizontally disposed within said lowerlevel; gas supply means selectively operable for supplying gas underoperating pressure to one end of said conduit section; a plurality ofgas discharge means spaced apart lengthwise of said conduit section fordischarging gas therefrom into said lower level when said gas supplymeans is in operation, said discharge means permitting flow of waterinto said conduit section for collection therein when said gas supplymeans is not in operation; and a valve device arranged adjacent an otherend of said conduit opposite to said one end and being responsive tooperation of said gas supply means for permitting discharge through saidother end of water collected in said conduit section when said gassupply means is returned to operation, for closing said other end uponmomentary interruption of operation of said gas supply means after saidcollected water is discharged and for maintaining said other end closedduring operation of said gas supply means after said momentaryinterruption.